Automatic telephone exchange



F. LUNDQUIST AUTOMATIC TELEPHONE EXCHANGE Origi nal Filed Aug. 16,

1'91? 4 Sheets-Sheet 1 yaw/aw F. A. LUNDQUIST AUTOMATIC TELEPHONEEXCHANGE Nov. 27 192-3.

Original Filed Aug. 16 1917 4 Sheets-Sheet 2 w/r/ fare/6 v4. 1

Nov. 27, 1923.

F. A. LUNDQUIST AUTOMATIC TELEPHONE Excmfier:

Original Filed Aug. 1 191'? 4 Sheets-Sheet 5 I Elf/67a??- m w 6 a. 1 9 4m 1 v & =7 w W 0 5 M m a 1 Z 6 Q J Z 1 1 w 2 M B r g 4 |w w W 3 w J J JJ H J mesa a." v

Nov. 27, 1923.

- F. A. LuNDQUIsT AUTOMATIC TELEPHONE EXCHANGE Original Filed Aug. 16

1917 4 Sheets-Sheet 4 Bria-KW? Fan/ ila %7f W W friable in number.

are initiated at the calling device but con- Patented Nov. 27, 1923.

siren sures FRANK A.- L Nnonrsr, orcnrcnco, ILLINOIS, AssIenoR, BY

TO HENRY s. CONRAD, TRUSTEE.

rcnsnn 'essrennnnrs,

AUToMArIcrnLEPHoNn EXCHANGE.

Application file d August is, 1517, Serial so. mans. Renewed April 19,1923.

To all to 710m it may concern Be it known that I; FRANK A. LUNDQUI'ST, acitizen of the United States of America, and a, resident otthe city'ofChicago, county of Cook and State of Illinois, have invented certain newand useful lihpiOvements in Automatic Telephone Exchanges, of which thefollowing is aspecification.

My invention relates to automatic telephone exchanges and has for itsobject improvements in such exchanges In telephone exchanges connectionsare made from place to place by trunk lines which are common for any oneof a. considerable number of subscribers, or a considerable number ofswitches representing subscribers. It is well known that the percentageof trunks required to carry the traflic decreases with the size of thegroup served by-the trunks. Thusfwhen subscribers (or switches) aredivided into groups of one hundred, the number of trunks required varies"from twelve to fifteen per cent of the number of subscribers, and isusually estimated at fourteen per cent. groups are as large asone'thousand, from four to six per cent is, enough. It is' here assumedas five per cent for'convenience of description.

But to divide subscribers into large groups requires the use of switchesof large size, that is switches with many contact pointsupon them. Theobjection to such switches is not so much the size ofthe switch itselfas the long rowsof contacts used on such switches and the length of timerequired to move. wipers over suchrowsby the step by step process. Tounderstand that objection it is necessary to consider the calling deviceat the subscribers station and the manner in which the subscriberoperates this device. The impulses occurring in the exchange in responseto operations of the calling device are of two kinds. First, those whichcorrespond in number to some number or figure directly indicated by thecalling device. Second, those used in hunting for an idle trunk andwhich are va- Those of the second class tin'ue automatically in theexchange until an idle trunk is found, For avariety of reasons it isClBSlIQblQtO makethe calllngdevice adhore'to the decimalsystem ofnotation, andhenceit is necessary, in large their the switches to addthe extra contacts on those rows over which the wipers are automaticallyadvanced. But subscribers habitually operate successive numbers ofrapidity whichmakes from fifteen to twenty contacts in a row aboutthelimit of what can be used; in practice. If more are used, subscribersget indicated impulses piled upon automatic impulses with the re sultthat there is a failure to make connections. One of the objects here isto provide Ways for operating switches so, that, in their automaticmovements, they can travel over long rows of contacts in the samelimited time now required in traveling .over short rows.

A typical organization on the plan here contemplated would'contain thefollowing apparatus for'an exchange often thousand subscribers. Therewould be ten thousand line switches (one for each subscriber) ar rangedin ten groups of one thousand switches ine'ach group. Each line switchwould have contacts for fifty trunks, and all of the line switches of agroup would be multipled to fifty trunks leading to fifty selectors, Itis practical to use such long rows of contacts on the line switchesoperating by the step by step principle because it is now thep'racticeto cause the line switch to automatically start into operation by merelylifting the receiver from the hook. There would be ten groups ofselectors with fifty switches in each group-each switch having fivehundred contact terminals in ten rows of fifty each. A special movementis provided for automatically selecting an idle one of the fiftyterminals in time not greater than that now employed in automaticallyselecting oneof twelve or fifteen.

There would also be ten groups of connectors with fifty switches in eachgroup-each connector having one thousand terminals reached in threemovements of the wipers. One of these movements is special for this typeo'f'connector. There would be no second selectors-a device now used inall auto matic exchanges of ten thousand capacity.

In the accompai'iyin'g drawings-i Fig. 1 is a condensed generalizeddiagram of part of an automatic telephone exchange arranged according tothe plan herein indicated;

Fig. 2 is a diagramof the selector used;

Fig. 3 is a diagram'of the connector;

Fig. 4 is a plan of a part of the selector, the wipers being advancedfrom normal position;

Fig. 5 is an elevation, partly in section, of a portion of the selector;and

Figs. 6 and 7 are details of the bank contacts used in the selector.

The apparatus at the local stations is the same as that now in commonuse in automatic telephone exchanges and consequently is not shown. Theline switches maybe any form of step by step apparatus which moveswipers over contacts, and are consequently onlyindicated by wipers andcontacts. Such wipers may be secured to the spindle of a ratchet wheelmoved by a magnet in a manner similar to that shown for the side switchin the upper part of Fig. 2. The line relays are presumed to operate inthe ordinary manner, and are only indicated. Other partsnot hereinafterfully described are assumed to be the same as those now in common use.

In Fig. 1 are shown three line switches provided with line wires 10 and11 leading to subscribers stations. Bridged between 10 and 11 are theline relays 12 and 13, and a battery X provided with a groundconnection. When a subscriber, as No. 1, removes his receiver heconnects his lines 10 and 11 together to energize his relays 12 and 13from battery X. This causes his wiper 14 to advance over its contactpoints until it finds the terminals of an idle trunk. When this occursthe wiper is stopped on such trunk, and the relay 13 has its connectionto battery and ground at some point as 15. The operation s0 far is ofthe ordinary and well known kindand needs no special description.

The trunk seized by a line switch is represented at the right of Fig. 2by the lines 16 and 17. When this connection is made a current flows asfollows: X12--10-local station11-141618-19ground-X.

This energizes relay 19 to attract its armature, whereupon a currentflows as follows: battery Y20212223242526groundY. Also a branch from 23to 27 and ground.

Relay 26 and release magnet 27 are copper sheathed and consequently areslow magnets which do not release their armatures under rapid make andbreak of their circuits; In other words, 26 and 27 hold their armaturesattracted during the sending of impulses to be described later.

Relays 19 and 26 close a circuit from the battery Y for the magnet 28 tooperate a ratchet wheel 29 as will be described later. Magnet 28 alsocloses a circuit as follows: battery Z-magnet 3031 3233groundZ. Magnet30 is also a slow magnet and com trols the advance oi the wipers 34, 24,35 and 36 which constitute the side switch of the selector. This sideswitch is similar to the ordinary side switch, and the parts are soarranged that the wipers 34, 24, 35 and 36 are simultaneously advancedwhen the magnet 30 is released.

When an impulse flowed thru the magnet 27 as before described, thearmature 37 was attracted to permit the driving pawl 38 and holding pawl39 to engage the ratchet wheel 40 or" the side switch. The driving pawl38 is connected to the armature lever '41 operated by magnet 30.

Connected to the armature lever 37 is a link 42 which rests on the headof a 'pin 43, said pin being normally supported in an elevated positionby a piston 44 in the ylinder 45. The space over the piston is connectedthru pipe 46 with a vacuum maintained by a suction pump. In pipe 46 is avalve 47 normally held closed by a spring 48 on the stem of the valve.When the armature 37 is attracted the end of the link 42 is moved clearof the end of the valve stem, and when the piston 44 descends in thecylinder 45, the end of link 42 drops to a level with the end of thestem of valve 47. When the armature'37 is later released, the spring onsaid armature overcomes the spring on the valve stem to open the valve47. Vvhen this occurs the vacuum over the piston 44 acts to raise it toits upper or normal position. In thus rising the piston 44 pushes up in43 to move link 42 clear of the end of the valve stem.

Secured to the piston 44 is a flat rod 49 having in it a hole 50, and aseries of other holes 51. (See Fig. 5.) Supported adjacent to therod 49is a hook 52 which nor mally engages the hole 50 and supports rod andpiston in the position shown in the drawings. The hook 52 has anarmature arranged to be acted upon by magnet 53 to release said hook andpermit piston and rod to fall by gravity. The piston 44 is somewhatloose in the cylinder ,45, and here is also a certain amount of air leakaround pin 43. This leak permits the piston to drop with a moderatedegree oi velocity when released, but is not enough to prevent the riseof the piston when the vacuum is applied by opening valve 47.

Pivoted at a convenient point is an arm 54 which is normally supportedin the position shown in Fig. 2, but is provided with an escapement 55operated by a magnet 56. Each time an impulse flows thru magnet 56 it.permits the arm 54 to fall by gravity one step. The outer Or free end ofarm 54 is adjacent to the rod 49 and has pivoted thereon a catch lever57 arranged to engage one or another of the holes 51 in rod 49. Innormal position aprojection on armature 37 engages a; tail piece oncatch lever 57 to hold said catch lever away "from rod 49. But whenarmature 37 is attracted by magnet 27, the projection moves away fromthe tail piece and permits catch 57 to engage any hole 51 which may atthe time be opposite the catch.

The upper end of the armature which carries hook 52 extends around therod 49 and hasa projection 58 which lies between said rod and a part ofthe body of the catch lever 57. Whenever the magnet 53 operates to moveits armature, the projection 58 pushes catch lever 57 away fromengagement with rod-49. Upon the actuation of magnet 53, the hook 52 isreleased and the rod 49 drops. As there is only one hole for the hook52, breaking the circuit at a latertime thru 53 lets the point of hook52 rub against theside of rod 49. In this position the projection58 isnot so far out as to prevent the catch 57 from engaging one of the holes51. But after such engagement of catch 57, an actuation of magnet 53'will cause projection 58 to release catch 57.

The bank contacts are arranged in ten vertical rows as shown in plan inFig. 4. The terminals for each line are represented by three contacts.the center one of which is the private contact and is longer than itstwo associates as shown in Figs. 4 and 7. The vertical rows containfifty, more or less, such terminals of three contacts each.

The lower end of the rod 49 enters the open end of a slotted tube 59upon the upper end of which is the ratchet wheel 29. The lower end ofthe rod 49 terminates in a ball 60 which is pivotally connected to ablock 61 arranged to slide vertically in the tube 59. On the block 61,and projecting laterally thru the slot in the side of the tube 59, aretwo contact carrying arms 62 and 63. The upper arm 62 carries the ordinary three wipers used in any ordinary trunk selecting switch. One ofthese three wipers is the private wiper, and the other two are thewipers which close the two sides of a. talking circuit. The lower armcarries an additional private wiper the purpose of which will be furtherexplaned hereinafter.

0n the lower end of the tube 59 is a spring 64 which normally turns saidtube so as to hold the arms 62 and 63 at the position shown in dottedlines in Fig. 4. On the armature 37 is an arm connected to a rod 65which normally rests upona holding pawl 66 and holds said pawlfrom-engagement with ratchet wheel 29. When however. armature 37 isattracted by magnet 27, the rod 65 is raised and the holding pawl 66 isfree to engage ratchet wheel 29. If. after this occurs, magnet 28 should0perate upon its armature 67, the driving pawl 68 will move the ratchetwheel 29 to advance arms 62 and 63, and thus bring their wipers over anydesired vertical row of contacts in the bank 69. In this turning,

the tube 59 revolves about but does not turn the rod 49. To make afairly accurate guide for the arms 62 and 63, the sides of the slot intube 59 are preferably provided with guiding flanges 169.

The magnet 27 is a slow magnet and holds its armature 37 attracted untilthe calling subscriber returns his receiver to its hook It will be seenby the foregoing description that the attraction of armature 37accomplishes several things. First, it releases the pawls for theratchet wheel 40 which controls the side switch; Second, it releases theholding pawl66 for the ratchet wheel 29. Third, it releases the catchlever 57 so that it may engage an opening in the rod 49. And fourth, itmoves the link 42 to the right to a position in which it can operateupon and open valve 47.

In making a call the subscriber removes his receiver which automaticallycloses a contact at the local station and b-rings'about thoseoperations, previously described,

which result in an impulse from battery-IQ reaching line. 16 (Fig. 2)and the conse quent operations of magnets 19, 26 and 27.

Magnets 28 and 30 are not operated by this first impulse reaching line16 because relay 19, in attracting its armature, breaks the circuit formagnet 28, and the circuit for magnet 30 is closed only by magnet 28.

The next thing-the subscriber does after removing his receiver is tooperate his calling device by pulling on its dial the first digit foundin the'number which represents the subscriber to be called. It will beas sumed that this is represented by the numeral 5; In doing this thesubscriber sends rapidly five impulses from battery X to relay 19 overthe path previously described. As the relay 19 is energized at thebeginning of this operation, the first impulse breaks and then remakesthe circuit for 19, and the last one of the five leaves the circuitclosed with the relay energized.

Because 26 and. 27 are slow, they hold their armatures attracted duringthe operation of relay 19. When the armature 20 of relay 19 falls backagainst its back Contact it closes the circuit for magnet 28, and when20 is again attracted the circuit is broken for 28. In other words,relay 19 and magnet 28- operate alternately. Each operation of magnet-28 advances the ratchet wheel 29 so as to move the arms 62 and 63'overthe vertical rows of contacts in bank 69. As we assumed 5 for the firstnumber, the completion of these impulses would leave arms 62 and 63 inthe position shown in full lines in Fig. 4.

As magnet 28 closes the circuit for the slow magnet 30, this last namedmagnet attracts its armature 41 and holds it until the circuit isfinally broken thru magnet '28.

When this occurs the retracting spring on armature 41 moves thatarmature to advance the side switch wipers .34, 24, 3'5 and 36 one stepfrom this position shown to the next contact points in their paths. Thisaction closes a circuit as follows :-battery Y-QO- 21-2223247071-magnet5372wiper 7 3 contact 74 with which wiper 73 is normally inengageinentgroundY.

The operation of magnet 53 releases. the hook 52 and at the same timecauses projection 58 to push catch on lever 57 away from the rod so thatsaid catch will not fall into any hole 51 in said rod. The release ofhook 52 permits rod 49 and connected parts to fall by gravity and thebrushes on arms 62 and 63 to travel along the contacts in the selectedfifth vertical row of bank 69.

As these parts tall, the wiper or brush 73 moves from contact tocontact. If the next private contact in the vertical row has a groundconnection the circuit thru magnet 53 will be maintained and the catchon lever 57 will be held'away from the rod 49. But when the wiper 73comes to'a private contact which has on it no ground connection, thenthe circuit will be broken thru magnet 53 and the catch on lever 57 willbe permitted to fall into a hole 51 and stop the further descent ofscend.

the rod 49 and connected wipers.

The magnet 53 has a second armature which closes a circuit at 77-73 formagnet 30 at the time when magnet is energized as just described. Thiscircuit is: Z-30-31 7 6-7 778groundZ. This attracts armature 41 asbefore so that when the circuit is again broken thru magnet 30 as aresult of brealo ing it thruv magnet 53, the retracting spring movesarmature 41 to again advance the side switch to bring wiper 34 oncontact 83.

In this last position a circuit is completed as follows :-batteryvV798081-568283 3485private wiper 86 grounded contact previously engagedand passed by the wiper 7 3, and thence back to battery W.

The actuation of magnet 56 operates the escapement 55 to permit the arm54 to de- As the armature of the magnet 56 makes and breaks its owncircuit at 8081, this descent is step by step. As the catch on lever 57is at this time in a hole 51 in rod 49, this descent lowers the wiperson said rod step by step from one contact to another. As long as thewiper 86 finds a grounded contact to engage with, the magnet 56 willcontinue its operation, but as soon as wiper 86 comes to a contacthaving no ground (which willbe the one previously engaged Icy-wiper 73),the circuit for magnet 56 will be permanently broken and the escapement55 will cease to operate.

The distance between the wipers 73 and 86 will usually be about two orthree steps of the escapement 55. The obj eat in using these two wipersand associated parts is to divide the long movement, over long rows ofcontacts, into two parts. The first of these is a rapid and continuousmovement terminating in an approximate selection of the first idletrunk. The second part consists in one, two, three or more steps, andterminates in an accurate selection of the first idle trunk. As long asthe approximate selection falls short of having the talking wipersconnect with the first idle trunk, it is immaterial to what extent itfalls short, provided it is within reasonable limits. A selector switchmay at one time fall short one step; at another time the same switch mayfall short two steps; and at still other times it may fall short threesteps. Whatever the shortage may be, the escapement 55 will make it upby the proper number of steps. As a consequence of this arrangement, nocareful adjustment of parts is necessary in terminating the first partof the automatic trunk selecting movement.

When the magnet 56 operates as previously described, it closes contacts87-88, thus completing a circuit as follows: battery Z3031768788groundZ.This again attracts armature 41, and when the circuit is finally brokenthru magnet 56, the wipers 01" the side switch are advanced to theirfinal position. In this position "the wiper 34 places ground connectionon the private wiper 86, and consequently on allmuitiple connections ofthe particular contact with which that wiper is at the time engaged. Inthis final position the wipers 35 and 36 connect to lines 17 and 16 fromthe line switch, and by means of wires 89 and 90 extend the connectionsto wipers 91 and 92 in engagement with trunk terminals in bank 69. Theterminals engaged are represented at the right of Fig. 3 by wires 93 and94.

In the position just described relays 95 and 96 of the connector areactuated from battery X over a circuit which includes ground and theconnections back to the local station. Relay 95 is a slow relay whichwill hold its armature attracted while the calling device is beingactuated manually to send rapid impulses thru magnet 96.

Upon relays 95 and 96 being actuated by reason of the side switch wipers35 and 36 connecting back thru the local station, these magnetsattracted their armatures. The circuit resulting is as follows :batteryX 979899100 and 146-groundX Magnet 100 is a slow magnet which will holdits armature attracted during rapid movements of armature 97. Theattraction of armature 101 by magnet 100 releases holding pawls 102,103, 104 and driving pawl 105 and lets these pawls engage theirrespective ratchets. Magnet 146 is also a slow magnet which holds itsarmature and controls a link 147 which corresponds to link 42. Theseparts control vacuum over the piston 135 in exactly the same way thatthe previously described parts control vacuum over the piston 44. p Theattraction of the armature 107 of relay 95 does not affect the operationof the switch in the first instance because the connection from batteryX is broken by the attraction of armature 97 of relay 96. But uponoperating the calling device at the local station the circuit for 96 isbroken and remade some definite number of times-from one to ten times.Upon the first break a circuit is completed as follows :X 971O6107108magnet 109110side switch wiper 1l1contact strip 112l13ground\:Also a branch extends from 108 as follows 114-side switch wiper115-116-magnet 117- gr0undX Magnet 109 is a slow magnet which holds itsarmature during the operations of relay 96 under impulses controlledfrom the calling device. Magnet 117, however, responds to these impulsesand attracts its armature 119 which carries pawl 120. This pawl operateson ratchet wheel 121 to turn tube 122. In this tube is a block 123having an arm 124 projecting thru a slot in the tube and carrying wipers125 and 126 adapted to engage selected contacts in the bank 127. Theseparts correspond to the similar parts in the selector switch previouslydescribed, and the number of impulses sent by the calling devicedetermine to what position the wipers shall be moved over the bank 127.The contacts in this bank are the line terminals for the subscribers inthe exchange, and are arranged in ten vertical rows. In a ten thousandexchange, each vertical row would contain terminals for one hundredstations.

Upon the completion ofa series of impulses due to operating the callingdevice at the local station, the circuit is left completed thru relay96. The consequent attraction of armature 97 breaks the circuit formagnet 109, whereupon its armature 118 falls back to advance the sideswitch wipers one step. Wiper 111 rests upon a continu ous strip 112 sothat the advance of this wiper changes nothing. Wiper 115, however, isshifted ;trom connection to magnet 117 to connection to magnet 128 sothat the next series of impulses sent by the calling device will flowthru the last named magnet.

Armature 129 of magnet 128 bears against a rod 130 which carries a pawl131 arranged to engage ratchet teeth on a slide 132. On the other end ofslide 132 is a pawl 133 which engages a notch in flat rod 134 connecledto piston 135 in cylinder 136. These parts are similar to partspreviously described for the selector switch.

In the rod 134 is a series of five pins 137 and a second series of fivepins 138. These pins are offset as shown and not in vertical arrangementover each other. The amount of offset from one pin to the next equalsthe spacing of the teeth on slide 132. Carried on said slide are pins139 and 140 which are arranged to cooperate with pins 137 and 138.

When magnet 128 moves the slide 132 one step to the left it movespin-139 under the lowest one of the pins 137 and at the same timereleases pawl 133 from rod 134. This permits rod 134 and connected partsto drop to a position which will bring the wipers 125 and 126 inengagement with the uppermost terminals in that particular row in bank127 which was previously selected by the operation of magnet 117. Whenmagnet 128 moves slide 132 the second step, pin 139 moves from itsposition under the lowest pin 137 to a position under the next pin 137and permits rod 134 and connected parts to again drop. The amount ofthis second drop is equal to the space occupied by ten sets of terminalsin bank 127 and leaves the wipers 125 and 126 in engagement with theeleventh set of terminals in the selected row. The third operation ofmagnet 128 permits the parts to again drop and come to rest with thewipers 125 and 126 on the twentyfirst set of terminals. And so on. Afterthe fifth drop, pin 140 comes under the lowest pin 138, and thensuccessively under the other pins.

The number of impulses sent by the calling device thru magnet 128 willdepend upon what group of ten terminal is wanted in the previouslyselected vertical row. lVhen this group is reached the impulses stop,and the side switch wiper 115 is advanced in the manner previouslydescribed from connection with magnet 128 to connection with magnet 141.This last magnet controls an escapement 142 which permits slide 143 tomove downward step by step as magnet 141 is operated. Slide 143 isguided by slots 144 operating on pins 145 secured in a convenient partof the frame work of the apparatus. The spacing of the ratchet teeth-inescapement- 142 corresponds to the spacing of the terminals in bank 127so that each operation of the magnet 141 lowers the wipers 125 and 126from one set of terminals to the next. This i made possible by carryingthe slide 132 on slide 143 so that lowering slide 143 lowers the rod 134and its connected parts.

The number of impulses sent by the calling device thru magnet 141depends upon the particular unit desired in the group of ten previouslyselected by magnet 128. hen the impulses thru magnet 141 stop, the sideswitch wipers 111 and 115 are advanced as before, but now rest uponblank contacts. Wire 148 connects wire 93 to wiper 125 and wire 149connects wire 94 to wiper 126. Hence it will be evident that' uponcompletion of the operations of magnet 141, the calling station will beconnected by wires 10 and 11, wires 16 and 17 wire 93 and 94, wires 148and 149, and wipers 125 and 126 with the terminals of a called stationas those terminals are found in bank 127.

Associated with wipers 125 and 126 there will be, of course, a. privatewiper and suitable connections for preventing interference with a busyline. Such private wiper and connections are well known things and formno part of the present invention. As a consequence they are notdescribed. he manner of signalling the called station is also a wellknown thing and not described.

When conversation is finished, the calling subscriber hangs up hisreceiver. The effect of this is to break the connection between lines 10and 11 in the ordinary manner. The effect of such break is to cause theline switch to return to normal position in a manner common in theprimary switches in ordinary automatic telephone exchanges. The detailsof the operations of the line switch for bringing about such return formno part of the present invention and are not described.

The breaking of the connection at the call ing station also breaks thecircuit for relay 19 and permits its armature 20 to fall back and thusbreak the circuit for the magnet 27. As a consequence of this lastbreak, the armature 37 falls back and the pawls 38 and 39 are liftedfrom engagement with the ratchet wheel 40. Thereupon the switch of: theselector returns to normal position in the ordinary manner.

The retraction of armature 37 causes the link 42 to engage the valvestem and open valve 47. This permits the air over piston 44 to be drawnout so as to cause the piston and connected parts to rise to normalposition. At its upper position the piston strikes pin 43 which. pusheslink 42 from engagement with the stem of valve 47. At the same time thehook 52 falls into the hole 50 and thus prevents the piston 44 fromfalling when the valve 47 closes. The same retraction of the armature 37causes rod to lift pawl 66 from ratchet wheel 29 so that spring 64 mayrotate the wiper arms 62 and 63 and associated parts back to normalposition.

The retraction of armature 37 does not immediately release the catch onlever 57 because the fall of rod 49 and arm 54 had carried the tailpiece 150 away from the arm 151 on armature 37. The catch on lever 57 isshown undercut at 152, and the lower edge of hole 51 in which this catchis engages this undercut and lifts arm 54 when the piston 44 rises. Inrising the piston 44 passes a little above its normal position and isstopped by engaging the boss in which pin 43 is located. 111 the extremeupper position of the piston 44 the arm 54 is raised high enough topermit the escapement 55 to catch in the lowest ratchet tooth as shownin Fig. 2. At this time the undercut 152 is still. in

side

engagement with the edge of the hole 51 in rod 49. The tail piece 150engages the arm 151 and moves the armature 37 as if it were attracted byits magnet 27. However, the other parts are in such a position that thismovement of armature 37 accomplishes nothing beyond putting tension onthe catch lever 57 at the undercut 152. \Vhen the valve 47 closes, thepiston settles down a short distance until stopped by the hook 52. Thissettling of the piston 44 and rod 49 releases the engagement with theundercut 152 and permits the retracting spring on armature 37 to movethe lever 57 to the position shown.

The breaking of the circuit at the calling station breaks it also forrelay 96 of the connector, which in turn breaks the circuit for magnets100 and 146. The consequent retraction of armature 101 lifts pawls 102,103 and 105. This permits the side switch, and ratchet 121 andassociated parts, to return to normal position as in the case of theselector.

The operation of magnet 146 moves the link 147 and results in the riseof piston 135 and connected parts exactly as the movement of link 42resulted in the rise of piston 44. ()n that part of the rod 134 whichextends below the horizontal extension 153 of the slide 143 is a collar154 which engages the under part of 153 and raises the slide to thenormal position shown in Fig. 3. Just as these parts are arriving attheir uppermost position the tail of the pawl 104 engages the adjacentpart of armature 101 so that pawl 104 is released and spring 155retracts the slide 132 to bring pawl 133 again into position to supportrod 134. These various movements leave the parts all in their originalposition from which they can be moved again for some other selection.

Fig. 3, which is principally diagrammatic, shows the pins 137, 138, 139and 140 as if they were all on one side of the rod 134. In practice itis preferable to have pins 137 and 139 on one side, and pins 138 and 140on the other side, with the rod 134 passing thru an opening in the slide132. The reason for this is simply to prevent interference of parts inthe restoring movement.

Fig. 1 shows, in much condensed form, a part of an exchange for tenthousand subscribers arranged in accordance with the plan outlined.No. 1. No. 2 and No. 3 represent connections to three line switches in agroup of one thousand such switches. The

wipers of these switches (represented by one wiper 14 for each switch)are arranged to sweep over fifty sets of terminals multiplie to the bankwires K. From these bank wires or trunks, taps 16 and 17 lead to fiftyselector switches, three of which are represented at A, B and C. Thenext group of one thousand line switches would lead in the lanes sameway to another bank of fifty trunks, and from these similar taps wouldlead to fifty other selectors constituting the second group.

By the operation previously described the side switch wipers 35 and 36are moved so as to extend the connections 16 and 17 to the selectorwipers, one of which is represented at 91 in Fig. 1. Each selector hasten vertical rows of trunk terminals with fifty trunk terminals in eachvertical row. Fig. 1 repre sents at 69 one such vertical row for each ofthe switches A, B and C. All of the trunk terminals of the firstvertical row of all of the selectors are multiplied together'and lead tothe fifty connectors in the first group, three of which are shown at L,M and N. The terminals of the second vertical row are similarlymultiplied together and lead to the fifty connectors of the secondgroup. And so on.

lVhen a selector switch is operated its wipers extend the connections tolines 93 and 95 in some connector, (L, or N), in a previously selectedgroup.

Each connector has terminals for one thousand subscribers lines, and theterminals in fifty connectors are multiplied together so that any one ofthe fifty connectors may complete connections to any one of the onethousand subscribers in the group. These ,erminals are placed in tenvertical rows with one hundred terminals in each row. A part of one ofsuch rows is shown at 127 in Fig.

1 for each of the connectors L, M and N.

The connections back from these terminals to the lines 10 and ll of thelocal Stations may be readily traced on Fig. l and need no specialdescription.

a I c aim s l, The combination with a long vertical row of terminals,and wipers for engaging such terminals, of pneumatic devices for movingsaid wipers upward and releasing devices for permitting them to movedownward by gravity, magnetic means for y rst Wiper,

controlling the pneumatic and releasing devices, and magnetlcallyoperated interce etin devices so arran ed as to cause said wipers tomove by successive long and short steps from one end of the row to aparticular terminal therein. I

The combination with a long row of contact terminals representingtrunks, of a wiper and carriage therefor, means for cans ing saidcarriage to advance rapidly so that said wiper will move from terminalto terminal in said row, means controlled by engagement of said wiperwith the terminal of an idle trunk for arresting the movement of thecarriage, a second wiper on said carriage, means for causing saidcarriage to move ev r. a ry a d eend W per to e men wit th erm al pre iu ly e g ed 'aad a moved when released, pins in offset arrangementextending from the side of said rod, an intercepting device arranged tobe engaged by said pins, means for moving the intercepting devicelaterally step by step so as to permit said rod to move axially step bystep, and separate neans for moving said intercepting device in adirection parallel with the axis of the rod so as to give said rod otherstep by step movements.

5 The combination with trunk terminals, a carriage having two wipers forengaging said terminals, and means forgiving said carriage a rapidmovement, of means con trolled thru one of said wipers for reducing thespeed of the carriage movement, and means controlled thru the otherwiper for stopping said movement.

6 The combination with trunk terminals, a carriageand means for givingit a move-' ment, and two wipers on said carriage for controlling suchmovement, one wiper being in advance of the other and normally activeand the rear Wiper being normally inactive, of meansby which upon theactive wiper engaging the terminal of an idle trunk the said activewiper will become inactive and the normally inactive wiper will becomeactive and at rest upon the terminal first engaged by 1 the forwardwiper. i i

7. The combination with trunk terminals and a movable switch having twotrunk hunting. wipers thereon for controlling the switch, one wiperbeing in advance of the other, of means by which upon the leading wiperengaging the terminals of an idle trunk such wiper will become inactiveand the control will pass to the following wiper through the terminalfirst engaged by the leading wiper.

8. The combination with trunk terminals, and a trunk huntingswitch, of:means by on the switch and later with another point on the switch to therear of the advanced pe 9, The combination with a series or" long rowsof trunk terminals, and wipers for ensaid terminals, of a step by stepdevice for moving said wipers from normal pe tien to a posit n adj ce to. a de i ed row of terminals, a continuous movement device foradvancing said wipers at high speed along the selected row of terminals,means for automatically stoppingsaid continuous movement device so as toarrest the wipers adjacent to but before reaching the terminals of anidle trunk, and a second step by step device for moving the wipers fromtheir arrested position to the idle trunk.

10. The combination with trunk terminails, a carriage having two wipersfor engaging said terminals, and means for giving said carriage a rapidmovement, of means controlled thru said wipers in succession forstopping said. carriage at a position corresponding to an idle trunk.

11. In a telephone system, trunk terminals divided into rows, said rowsdivided into groups, wipers for engaging said terminals, means forrotating said wipers step by step into alignment with a desired one ofsaid rows, a rod, said wipers secured to said rod but rotatableindependent thereof, said rod arranged to be moved by gravity whenreleased, arms on said rod staggered diagonally and spaced from eachother a distance equal to the length of one of said groups, anintercepting device arranged to be on gaged by said arms, means formoving the intercepting device step by step in one direction so as topermit said rod to move step by step lected row, and additional meansfor moving the intercepting device step by step in a different directionto select a desired terminal in the selected group.

1:2. In a telephone system, trunk terminals divided into rows, said rowsdivided into groups, wipers for engaging said terminals, means forrotating said wipers into alinement with a desired one of said rows, arod, said wipers secured thereto but rotatable independent thereof, saidrod a'r ranged to be moved by gravity when released, arms on said rodstaggered diagonally and spaced from each other the distance equal tothe length of one of said groups, an intercepting device arranged to beengaged by said arms, means for moving the intercepting device in onedirection so as to permit said rod to move said wipers to select a.desired group in the selected row, and separate means for moving theintercepting device in a different direction to move said wipers toselect. a desired terminal in the group.

13. In a telephone system, trunk terminals divided into rows, said rowsdivided into groups, wipers :for engaging said terminals, means "forrotating said wipers into alinement with a desired one of said rows, arod, said wipers secured to said red but rotatable independent thereof,an intercepting device, means for moving the intercepting device so asto permit said rod to make to select a desired group in the se-.

a corresponding number of movements to move said wipers opposite adesired group in the selected row, and additional means for againoperating said intercepting device to move said wipers in engagementwith a desired terminal in the selected group.

it. In a telephone system, trunk terminals divided into rows, said rowsdivided into groups, wipers for engaging said terminals, means forrotating said wipers into alinement with a desired one of said rows, arod, said wipers secured to said rod but rotatable independent thereof,an intercepting device, means for moving the intercepting device anumber of steps so as to permit said rod to move said wipers acorresponding number of steps opposite a desired'group in the selectedrow, and additional means for again operating said intercepting devicein a differentdirection to move said wipers step by step into engagementwith a desired terminal in the selected group.

15. The combination with trunk terminals, and a trunk hunting switchhaving two trunk hunting wipers one of which is in ad Vance of theother, of means by which the terminal of an idle trunk co-operatesinitially with said advanced wiper and later with said other wiper toallow said switch to some to rest on said idle trunk.

16. The combination with trunk termi nals, a carriage having two wipersfor engagement with said terminals, one or" said wipers being in advanceof the other wiper, and means for giving said carriage a rapid movement,of means by which said advanced wiper controls the extent of travel ofsaid carriage in its rapid movement, of means for switching the controlof the movement of the carriage from said advanced wiper to the otherwiper, and of means controlled through said other wiper for moving saidcarriage step by step and for stopping said carriage at a positioncorresponding to an idle trunk.

17. The combination with a long row of contact terminals representingtrunks, of a wiper and carriage therefor, means for causing saidcarriage to advance rapidly so that said wiper will move from terminalto terminal in said row, means controlled by engagement of said wiperwith the terminal of an idle trunk for arresting the movement of thecarriage, a second wiper on said carriage, means under control oi saidsecond wiper for moving said carriage step by step until said secondwiper comes into engagement with said terminal previously engaged bysaid first wiper, and automatic means for again arresting said carriagewhen said second wiper engages said terminal.

18. In a telephone system, trunk terminals, a carriage having two wipersfor engaging said terminals, means for rotating said carriage to placesaid wipers in alinement with a desired row of said terminals, a catchfor holding said carriage in elevated position, means or operating saidcatch to allow, a rapid movement of said carriage, means controlledthrough one of said Wipers for reducing the speed of the carriagemovement when said one Wiper engages an idle trunk terminal, and meanscontrolled through the other of said wipers for continuing said movementby a step by step movement until said other wiper. engages with saididle trunk terminal.

19. In an automatic telephone exchange, the combination with trunkterminals and wipers designed to make electrical connection with saidterminals, of means for moving said Wipers to automatically select anidle trunk, such movement being divided into two parts, the first partunder control of one of said wipers and being a rapid continuousmovement terminating in the approximate selection of an idle trunk, andthe second part under control of a second of said Wipers being a slowerstep by step movement in the same direction Which terminates in anaccurate selection of said idle trunk.

20. The combination with line terminals, and wipers for engaging saidterminals, two of said Wipers being trunk hunting Wipers, of means forpermitting said wipers to fall by gravity toward a desired terminal,means under control of one of said trunk huntin wipers for stopping suchfall when said wipers are Within a short distance of the desiredterminal, and a device under con-' trol of the second trunk huntingWiper for moving said wipers etc by step in the same direction fromstoppe position to the desired terminal.

FRANK A. LUNDQUI ST.

